When someone makes a GUI frontend to Wikipedia, those features will become more sophisticated (wysiwyg).
Blasphemy! GUI? WYSIWYG? Now that would be unwiki.
Seriously; one of the reasons why we are successful is because there is a bit of a learning curve to being a contributor (small, but it is there). I hate to say it, but this small learning curve acts as a kind of filter against those that have nothing but incoherent and random nonsense to "contribute".
If the basic concept ain't broke, why fix it? Wiki is dead easy to learn anyway. But it does require some cognitive faculty and mental discipline to get the hang of.
While I'm receptive to the "pons asinorum" argument, I rather like the idea of a GUI wiki interface someday. That's why I want to get the markup language adequately specified and unambiguous, and why I entered a feature request for myself to design a stable API for fetching and editing pages. We'll just make sure that setting up the GUI application requires them to enter a URL or something. :-)